Art of refining hydrocarbons



May 9, 1933. E. c. HERTHEL 1,908,606

ART OF REFINING HYDROCARBONS Filed Sept. 14, 1928 ATI'ORNEY5 Winnie:

um'rsu s'ra'rss mama-- PATENT omcs or chrome. rumors. Assreron re snrcmra ammo This invention relates to improvements in the'manufacture of gasoline; more particularl the invention relates to improvements in the combined vafpor phase cracking of 011 to produce motor uel gasoline and refining of the .thus produced gasoline by passage tllilrough an 'adsorptive catalyst in vapor ase. The products of operations in which relatively severe cracking conditions are maintained include, if the conditions are appropriate, constituents of special value as components of motor fuel. With many more refractory'stocks, such as kerosene and light 16 gas oil,' the more advanta us range of cracking temperatures lies a vs. the critical temperature of this stock so that the opera tion must be carried'out substantially in the vapor phase if suchrelatively severe cracking 20 conditions are maintained. With heavier and higher boiling stocks, such .as heavy gas oil, the more advantageous range of cracking temperatures may not lie wholly above the critical tem rature of the stock but even in such cases pressures nry to maintain any substantial part of the stock in 1i uid phase are usually extremely high. ThlS invention relates garticularly to combined o rations in whic oil is heated in the vapor so p ase to a high cracking temperature, that is to a cracking temperature upwards of 900 F.

These constituents of special value as components of motorfuel are unsaturated and, in

raw cracked gasoline so produced, are associated with other unsaturated constituents such as the di-olefines which are not suitable as components of motor fuel. When such raw 0 ed gasoline is passed in vappr phase through an adsorptive catal st suc as ful- 40 lers earth, these objections 1e unsaturated constituents are selectively polymerized to form higher boiling polymers. This reaction thus affords a means of separating such objectionable unsaturated constituents with- 4 out involving loss of other unsaturated constituents of special value as components of motor fuel.

In the manufacture of gasoline containin these unsaturated constituents of cial va no as components of motor fuel, it as previousl been pro d to subject the raw crac ed va rs om the vapor phase cracking operation first to a fractionating operation and then to pass the vapors esca ing from the fractionating o ration throug an adsorptive catalyst to e ect the polymerization of objectionable unsaturated constituents. This fractionating o eration has usually been carried out for ei er or both of two purposes; to separate from the raw cracked vapors for return to the cracking o oration constituents higher boiling than suitable as components of the soline product but suitable again to be 5 bjected to the cracking operation, and to separate from the raw cracked va rs all constituents higher boiling than suitable as com onents of the Ezsoline product to produce irectly a gasoe of the desired boiling range. rrespective of purpose, it has been common practice to control such fractionating operations by introducing directly into the vapors in the fractionati operation a .part of the final gasoline pr uct.

This scheme of operation has several advantages so far as efl'ecting or promoting accurate fractionation of the vapor mixture subjected to the fractionating o eration is concerned, but in combinedvapor p ase cracking and vapor phase refining operation in which the raw cracked vapors are passed successively through the fractionating operationand then through an adsc.-ptive catalyst it has a number of disadvantages. In carryilig out this scheme of operation, that part 0 the final gasoline product reintroduced into the va rs in the fractionating operation is reva razed therein and again contacted with t e-adsorptive catalyst in admixture with the vapors esca from the fraction atinfinoperation, an this returned art of the a to repeated contact with theadsorptive ,catalyst. This repeated contact usually involves severe and excessive losses, apparently due to the instability of unsaturated constituents of the cracked product, and these losses are doubly severe because they usually constitute a loss of unsaturated constituents of special value as components of motor fuel.

gasoline product is thus an 'ected- This invention provides an im roved method of operation which, althoug providing for accuratel controlled fractionation in this combine vapor phase cracking and vapor phase refining o eration, eliminates such losses, and which as several further important advantages.

According to the present invention, in combined vaporphase cracking and vapor phase refining operations in which the raw cracked vapors are passed successively through a fractionating operation and then through an adsorptive catalyst, a partial condensate is roduced from the vapors escaping from the ractionating operation before they contact with the adsorptive catalyst b indirect heat exchange with a cooling me ium, such as water or such as raw oil to be supplied to the cracking operation proper, and the fractionating operation is controlled by introducing this condensate into direct contact with t e vapors in the fractionating operation. The invention thus afi'ords accurate control of the fractionating operation and at the same time avoids recontacting with the adsorptive catalyst in the refining operation any part of the final gasoline product condensed from the vapors escaping from the iractionating operation which have been sub- ]ected to the refining operation.

The invention will be further described in connection with the accompanying drawings which illustrate, in a diagrammatic and conventional manner, one form of apparatus adapted for carr ing out the process of invention, but it is intended and will be understood that this further description and illustration are for the purpose of exemplification ferring to the drawing, the apparatus illustrated includes a fractionating tower 1, a condenser 2, a refining tower 3, another condenser 4, and a receiver 5. Raw cracked vapors from the apparatus in which the vapor phase cracking o eration proper is carried out are supplie to the lower end of tower 1 through connection 6, vapors escaping from the up er end of tower 1 are conveyed to the condenser 2 through connection 7 and vapors escaping from the condenser 2 are conveyed to the refining tower 3 through connection 8, vapors escapin from the refining tower 3 are conveyed t rough connection 9 to the condenser 4, and, after separation from any uncondensed vapors and gases in the receiver 5, the condensate produced in condenser 4 is discharged through connection 10. A charge of an adsorptive catalyst, 40-60 or 60-80 mesh fullers earth for example, is su ported upon a foraminous partition 11 in t e refining tower 3. The vapors to be subjected to the refining operation may be passed either upwardly or downwardly through this char e of the adsorptive catalyst by means 0 the branch, connections r shown. Polymers (produced by the vaporcatal st contact an other high boiling materia separated in the tower 3 are discharged through connection 12. A suitable cooling medium is circulated at an approximately produced in the fractionating tower 18 re-' turned to the cracking operation, may also be introduced into the tower 1 at an intermediate point through connection 17. The condensate or condensate mixture produced in the tower 1 is discharged through connection 18.

The apparatus illustrated ma be connected directly to a vapor phase crac ing apparatus such as that described in an application filed June 13, 1927, by Harry Pelzer, Serial No. 198,621. For examp e the vapor mixture escaping fromthe scrubbing tower or from a subsequent reflux tower or fractionating tower in that apparatus may be supplied to tower 1 through connection 6 and the condensate or condensate mixture discharge from tower 1 through connection 18 may be supplied to the heater or to the upper end of the scrubbing tower or to the upper end of a subsequent reflux tower or refractionating tower in that apparatus.

In carrying out the present invention in the apparatus illustrated, the raw cracked vapors from the vapor phase cracking operation are passed successively through the fractionating tower 1 and then through the charge of the adsorptive catalyst in the refining tower 3 and the fractionating operation carried out in the fractionating tower 1 is controlled by introducing directly into the upper end of this fractionating tower a artial condensate produced in condenser 2 10m the vapors escaping from the upper end of the fractionating tower 1 before they contact with the adsorptive catalyst in the refining tower 3. This control may be effected, for example, by regulating the rate of circulation of the cooling medium through the cooling coil 13 so that this partial condensate is produced from the raw vapor mixture at a rate not less than the maximum rate at which this condensate is required to be supplied to the fractionating operation and by regulating, by means of the valves in connections 15 and 16, the proportion of this condensate introduced directly into the upper end of the fractionating tower 1 through connection 15 and the proportion discharged through connection 16. Or, for example, this control may be eflected by regulating the rate of circulation of the cooling medium or the temperature of the cooling medium circulated through the cooling coil 13, or by regulating this rate or this temperature conjointly with regulation of the proportion of the partial condensate supplied to the fractionating operation through connection 15 and discharged through connection 16.

The fractionating operation preceding the refining operation, the fractionating operation carried out in tower 1 of the apparatus illustrated for example, may be controlled so that the vapors escaping from the refining operation when condensed form afinal refined gasoline product of the desired boiling range, or the fractionating operation preceding the refining operation, the refining operation carried out in tower 1 in the apparatus illustrated for example, may be controlled so that the vapor mixture escaping from the refining operation includes only 50-75%, for example, of the desired gasoline product and this vapor mixture may then be subjected to a further fractionating operation controlled to produce a final gasoline product of the desired boiling range. The refining operation may be combined with a subsequent fractionating operation, for example, as described in my application filed February 29, 1928,'Serial No. 257,958.

I claim: I

In combined vapor phase cracking and vapor phase refining operations in which the raw cracked vapors are, passed successively through a fractionating operation and then through an adsorptive catalyst, the improvement which comprises producing a partial condensate from the vapors escaping from the fractionating operation before they con tact with the adsorptive catalyst by indirect heat exchange with a cooling medium, introducing this condensate into direct contact with the vapors in the fractionating operation, and controlling the fractionating operation by independently regulating the amount of condensate thus introduced thereto.

In testimony whereof I ailix my si ature.

EUGENE C. HERT EL. 

